The present invention relates to a polishing machine for polishing the peripheral edge of a semiconductor wafer.
The peripheral edges of semiconductor wafers made from silicon and the like are chamfered, but in recent years, further polishing of the peripheral edge has come to be conducted in order to prevent particle formation on the peripheral edge, imperfections arising during handling, and the like. Edge processing methods are known, for example, a method for rotating a semiconductor wafer, and pressing a similarly rotating polishing pad thereto, while supplying polishing solution, as described in Japanese Patent Laid-Open Publication No. Hei. 11-104942, and a method for pressing a rotating polishing pad to a plurality of stacked semiconductor wafers, while supplying polishing solution thereto, as described in Japanese Patent Laid-Open Publication No. Hei. 05-182939.
Chamfering processes of the peripheral edge of semiconductor wafers have had the following problems, due to the fact that the chamfering radius is small and the chamfering corners are steeply inclined: even with a flexible polishing pad it is unfeasible to obtain uniform contact with the surface of the peripheral edge, making it difficult to obtain highly precise polishing, and because only a small part of the surface of the pad is in contact with the edge surface, for instance a point or a line, the polishing process is inefficient. Additionally, constant adjustments were required in order to maintain favorable polishing conditions, including changing the polishing pad at appropriate intervals.